Tue Apr 20, 2021 8:59 am
Tue Apr 20, 2021 10:15 am
Tue Apr 20, 2021 5:25 pm
93celicaconv wrote:How much different is the engine control from original now? Your referenced AFR - do you control with that or only monitor it? Your AFR is telling you that you are very lean when having the problem. If you are still controlling with an original O2 sensor system, your O2 sensor may be going out on you. And yes, low fuel pressure is also a source problem.
Tue Apr 20, 2021 5:40 pm
Tue Apr 20, 2021 6:09 pm
Tue Apr 20, 2021 6:22 pm
underscore wrote:Trying to diagnose intermittent problems can be a pain. I'd guess possibly a small vacuum leak but I think the gen 3 system is okay with leaks?
Tue Apr 20, 2021 7:43 pm
underscore wrote:Trying to diagnose intermittent problems can be a pain. I'd guess possibly a small vacuum leak but I think the gen 3 system is okay with leaks? If it's happening more when warmed up maybe try jumping the fuel pump in the diagnostic box to take the relays out of the equation. I had a defective one in the engine bay fuse box and the engine would start dying randomly once it was properly warmed up.
Tue Apr 20, 2021 7:43 pm
grip-addict wrote:OE wiring to the fuel pump ?
Tue Apr 20, 2021 8:46 pm
Tue Apr 20, 2021 10:48 pm
grip-addict wrote:On my car I noticed significant voltage drops when the pump was under even minor load, like boosting 5 psi, so that's why I asked about wiring. But, I misread your post and thought you had an uprated pump when it's not clear if you do.
If your pump IS bigger than stock, then you definitely need bigger gauge wiring to the pump.
It can be hard to tell if it IS a fuel issue or not without a fuel pressure gauge. If you were thinking about getting one, now is a good time to.
I will ask though - how new is your fuel filter?
Wed Apr 21, 2021 2:56 am
93celicaconv wrote:An air leak on a Gen 2 3S-GTE would affect idle quality, without doubt, given it's fuel map is based on an AFM.
Wed Apr 21, 2021 5:00 pm
Wed Apr 21, 2021 5:52 pm
Wed Apr 21, 2021 6:08 pm
grip-addict wrote:I recently had to replace my FPR on my gen3 3s because fuel pressure wasn't rising with boost. It just sat static... ugh.
I have a gen2 3s that I stole the FPR from. Same issue.
Ended up going with an aeromotive fpr and after that and running bigger gauge wire to my walbro255 it's golden.
Do you get the issue when free revving and taking off from a stop WITHOUT boost?
BTW when NOT boosting you should have more fuel pressure if the FPR's vac reference line isn't hooked up.
Then once boosting, the fuel pressure should rise IF the line is hooked up.
You can also test it by bridging fp and b+ to run the pump when the car is off and then putting shop air (regulate it down to different boost values your engine sees and check the gauge results) on the vacuum nipple of the FPR. Check fuel pressure and you should see it rise when the air's on the fpr nipple.
My gen2 and gen3 FPR's WERE increasing the pressure with the shop air, but they were too slow to respond and were causing tuning headaches.
Wed Apr 21, 2021 6:39 pm
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